'e 未定义'调用 image() 时出错

Question

当我从 p5.js 库调用 image() 时，它给出了类型错误“e is undefined”，尽管给了它图像。我对 javascript 相当陌生，对 p5.js 也完全陌生。我的想法是让以下图像从随机的 x 和 y 坐标落在屏幕上。

var yVal; 
var accel; 
var velocity; 
var mass; 
var pieces = []

function preload () {
   images = ["/images/L.png", "/images/LL.png", "/images/T.png"]
   img_amount = getRandomInt(21);
   for (var i = 1; i <= img_amount; i++) {
       var img = loadImage(images[getRandomInt(3)]);
       pieces[i-1] = img;
   }
}

function setup() {
 createCanvas(window.innerWidth, 700);

 yVal = [];  
 velocity = []; 
 mass = 10; 
 accel = mass * 0.1; 

 for (var i = 0; i <= img_amount; i++) {
   var randX = getRandomInt(window.innerWidth);
   var randY = getRandomInt(700);
   image(pieces[i], randX, randY, mass, mass);
 }
}

function draw() {
 background(25);
 fill(255,0,0);

  for (var i = 0; i <= img_amount; i++) {
    velocity[i] += accel;
    yVal[i] += velocity[i]; 
    image(pieces[i], pieces[i].xvalue, yVal[i], mass, mass);
    if (yVal[i] > height - mass/2) {
        // A little dampening when hitting the bottom
        velocity[i] *= -0.6;
        yVal[i] = height - mass/2;
    }
  }
}


function getRandomInt(max) {
    return Math.floor(Math.random() * max);
}